British Prime Minister Theresa May has called for a law to make "upskirting" a criminal offence in England and Wales.

It comes after one of her own MPs, Sir Christopher Chope, blocked attempts to outlaw it on Friday.

He shouted "object" in the British parliament as the private member's bill was being discussed and this was enough to derail it.

Upskirting is the act of secretly photographing underneath someone's skirt without permission, often with a mobile phone.

Sir Christopher's intervention prompted cries of "shame" from other MPs and May later took to Twitter to make her views clear.

"Upskirting is an invasion of privacy which leaves victims feeling degraded and distressed," she wrote.

"I am disappointed the bill didn't make progress in the Commons today, and I want to see these measures pass through Parliament - with government support - soon."

Government backing

The government had previously backed the legislative proposal, which was expected to sail through parliament.

Justice minister Lucy Frazer said beforehand: "By making upskirting a specific offence, we are sending a clear message that this behaviour will not be tolerated and that perpetrators will be properly punished."

However, it only takes one MP to shout "objection" in Parliament to halt a bill's progress.

Gina Martin, who launched a campaign demanding change, said she was "obviously extremely upset and disappointed that Chope decided to object on this vitally important bill".

The 26-year-old experienced upskirting at a British music festival and lobbied to "close the gap in the law" using the hashtag #stopskirtingtheissue.

Martin said she remained positive, though, and that she and her lawyer had organised a meeting with Chope to discuss the bill.

"I'm positive and hopeful he'll become a supporter," she said.

What is the bill?

Liberal Democrat MP Wera Hobhouse introduced the measure in Parliament as part of the Voyeurism (Offences) Bill.

It would see upskirting fall in line with voyeurism offences, meaning perpetrators could face up to two years in jail.

Victims currently have to seek prosecution through either the offence of outraging public decency or as a crime of voyeurism under the Sexual Offences Act.

However, campaigners argue that current legislation does not adequately cover the practice.

Scotland has already banned upskirting.

Mayor of London Sadiq Khan previously tweeted his backing for the bill saying: "I welcome the Government’s support for @beaniegigi’s (Martin) excellent campaign."